Takes a while for people to learn. That time is way more expensive for everyone involved because it also costs you on the mentor side. I've figured out a thing: lots of strong engineers want to work with other strong engineers. They want to execute. So I give them that and they leave places where they spend most of their time trying to support or teach other people.

And if someone is too junior based on our initial phone call, I just direct them elsewhere and hit then up two years later when those guys have mentored them. Way easier.